Integrated active/passive visible/uv modulator

ABSTRACT

Integrated passive/active modulator units, integrated passive/active modulators comprising one or more units, and corresponding methods of fabrication and use are provided. In an example embodiment, a unit comprises an upstream passive portion comprising a passive waveguide; a downstream passive portion comprising a continuation of the passive waveguide; and an active portion between the upstream passive portion and the downstream passive portion. The active portion comprises an active waveguide and electrical contacts in electrical communication with the active waveguide. The active waveguide comprises an upstream taper and/or a downstream taper. The upstream taper is configured to optically couple the active waveguide to the passive waveguide of the upstream portion and the downstream taper is configured to optically couple the active waveguide to the continuation of the passive waveguide of the downstream portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/683,335, filed Nov. 14, 2019, the content of which is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

Various embodiments relate to integrated active/passive modulators forvisible and/or ultraviolet (UV) wavelengths and methods of fabricationthereof.

BACKGROUND

In various applications, photonic beams may be modulated. Suchmodulation may include switching the intensity of the photonic beams onand off, temporal power shaping, feedback, phase modulation, andfrequency modulation. Such photonic beam modulation is oftenaccomplished using free space acoustic-optics modulators (AOMs) and/orfree space electro-optic modulators (EOMs). Through applied effort,ingenuity, and innovation many deficiencies of such systems have beensolved by developing solutions that are structured in accordance withthe embodiments of the present invention, many examples of which aredescribed in detail herein.

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS

Example embodiments provide integrated active/passive modulators forvisible and/or ultraviolet (UV) wavelengths. Example embodiments provideintegrated active/passive modulator units, integrated active/passivemodulators comprising one or more integrated passive/active modulatorunits, corresponding methods of fabrication and/or use, and/or the like.Various embodiments provide integrated active/passive modulators for usewith wavelengths in the range of approximately 350-1000 nm.

According to one aspect, an integrated passive/active modulator unit isprovided. In an example embodiment, an integrated passive/activemodulator unit comprises an upstream passive portion comprising apassive waveguide; a downstream passive portion comprising acontinuation of the passive waveguide; and an active portion between theupstream passive portion and the downstream passive portion. The activeportion comprises an active waveguide and electrical contacts inelectrical communication with the active waveguide. The active waveguidecomprises at least one of (a) an upstream taper or (b) a downstreamtaper. If present, the upstream taper is configured to optically couplethe active waveguide to the passive waveguide of the upstream portion.If present, the downstream taper is configured to optically couple theactive waveguide to the continuation of the passive waveguide of thedownstream portion.

In an example embodiment, the active waveguide is made of a firstmaterial, the first material characterized by the refractive index ofthe first material changing in response to an electrical signal appliedto the electrical contacts. In an example embodiment, the first materialcomprises at least one of LiNbO₃, ZrO₂ doped LiNbO₃, LiTaO₃, MgO dopedLiTaO₃, or BaTiO₃. In an example embodiment, the passive waveguide ismade of second material comprising at least one of Al₂O₃, Si₃N₄, HfO₂,AlN, or Ta₂O₅. In an example embodiment, the upstream passive portion,the downstream passive portion, and the active portion further comprisea first cladding layer disposed between a substrate and the passivewaveguide and a second cladding layer that, with the first claddinglayer, encloses the passive waveguide. In an example embodiment, thefirst and second cladding layers are oxide layers. In an exampleembodiment, the upstream taper and/or downstream taper extends outwardalong a unit axis defined by a beam propagation direction through theintegrated passive/active modulator unit; in the upstream taper, theactive waveguide widens from a upstream taper end width at the upstreamend of the active waveguide to a primary active waveguide width at acentral region of the active waveguide; and in the downstream taper, theactive waveguide narrows from the primary active waveguide width at thecentral region of the active waveguide to a downstream taper end width.

According to another aspect, an integrated passive/active modulator isprovided. In an example embodiment, an integrated passive/activemodulator comprises at least one passive/active modulator unit and atleast one additional passive waveguide. The at least one passive/activemodulator unit comprises an upstream passive portion comprising apassive waveguide; a downstream passive portion comprising acontinuation of the passive waveguide; and an active portion between theupstream passive portion and the downstream passive portion. The activeportion comprises an active waveguide and electrical contacts inelectrical communication with the active waveguide. The active waveguidecomprises at least one of (a) an upstream taper or (b) a downstreamtaper. If present, the upstream taper is configured to optically couplethe active waveguide to the passive waveguide of the upstream portion.If present, the downstream taper is configured to optically couple theactive waveguide to the continuation of the passive waveguide of thedownstream portion. The at least one additional passive waveguide isoptically coupled to the upstream passive portion and the downstreampassive portion via one or more beam splitters and/or beam combiners.

In an example embodiment, the at least one passive/active modulator unitcomprises a pair of passive active/modulator units coupled to oneanother in parallel. In an example embodiment, the at least onepassive/active modulator unit comprises two or more pairs of passiveactive/modulator units, each pair of passive/active modulator unitscoupled in parallel, and a first pair of passive/active modulator unitsserially coupled to a second pair of passive/active modulator units. Inan example embodiment, the at least one unit is formed into a ring suchthat both the upstream passive portion and the downstream passiveportion are coupled to a same additional passive waveguide. In anexample embodiment, the at least one additional passive waveguidecomprises a through passive waveguide and a ring passive waveguide, thering passive waveguide is configured to couple light into and out of thethrough passive waveguide, and the at least one unit is formed into aring such that both the upstream passive portion and the downstreampassive portion are coupled to the ring passive waveguide. In an exampleembodiment, the at least one integrated passive/active modulator unitcomprises at least two integrated passive/active modulator units eachformed into a ring such that both the upstream portion and thedownstream portion of a first unit of the at least two integratedpassive/active modulator units are coupled to a same additional passivewaveguide and both the upstream portion and the downstream portion of asecond unit of the at least two integrated passive/active modulatorunits are coupled to the same additional passive waveguide, and thefirst unit and the second unit are serially coupled to the sameadditional passive waveguide. In an example embodiment, the integratedpassive/active modulator is configured to provide a combined output beamthat can be modulated between a high intensity/on state and a lowintensity/off state with a frequency of at least approximately 100 MHz.In an example embodiment, the integrated passive/active modulator isconfigured to provide a combined output beam that has an extinctionratio between a high intensity/on state and a low intensity/off state ofat least approximately 40 dB.

According to still another aspect, a method of fabricating an integratedpassive/active modulator is provided. In an example embodiment, themethod comprises depositing a first cladding layer on a substrate;depositing a passive waveguide layer on the first cladding layer andpatterning the passive waveguide layer to provide a passive waveguide;depositing a second cladding layer on the passive waveguide and thefirst cladding layer so as to enclose the passive waveguide; defining anactive portion of an integrated passive/active modulator unit by bondingan active layer to a portion of the second cladding layer; etching theactive layer to form an active waveguide comprising at least one of anupstream taper or a downstream taper; and depositing and patterningelectrical contacts in electrical communication with the activewaveguide.

In an example embodiment, the method further comprises depositing athird cladding layer on the active portion; and etching via openings inthe third cladding layer, wherein the electrical contacts are at leastpartially disposed within the via openings. In an example embodiment,the active layer is made of a first material, the first materialcharacterized by the refractive index of the first material changing inresponse to an electrical signal applied to the electrical contacts. Inan example embodiment, the first material comprises at least one ofLiNbO₃, ZrO₂ doped LiNbO₃, LiTaO₃, MgO doped LiTaO₃, or BaTiO₃. In anexample embodiment, the passive waveguide is made of second materialcomprising at least one of Al₂O₃, Si₃N₄, HfO₂, AlN, or Ta₂O₅. In anexample embodiment, the passive waveguide layer and/or the activewaveguide layer is/are patterned to form a passive waveguide and/oractive waveguide, respectively, having a cross-sectional area in across-section taken substantially perpendicular to a unit axis of theintegrated passive/active modulator where the cross-sectional area isconfigured such that when a photonic beam characterized by a wavelengthin a range of approximately 350-1000 nm and having a power in a range ofapproximately 100-300 mW propagates through and/or is modulated by theintegrated passive/active modulator, the intensity of the photonic beamin a unit area of the passive waveguide and/or active waveguide is lessthan a damage threshold intensity for a material of the passivewaveguide and/or active waveguide, respectively.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 provides block diagram of an example integrated passive/activemodulator unit, in accordance with an example embodiment.

FIG. 2 provides a perspective view of an example integratedpassive/active modulator unit, in accordance with an example embodiment.

FIG. 3 provides a cross-sectional view of a passive portion of theexample integrated passive/active modulator unit taken at line AA ofFIG. 2, in accordance with an example embodiment.

FIG. 4 provides a cross-sectional view of an active portion of theexample integrated passive active modular unit taken at line BB of FIG.2, in accordance with an example embodiment.

FIG. 5 provides a schematic diagram of a Mach-Zehnder Interferometer(MZI) modulator comprising two integrated passive/active modulatorunits, in accordance with an example embodiment.

FIG. 6 provides a schematic diagram of a cascaded MZI modulatorcomprising four integrated passive/active modular units, in accordancewith an example embodiment.

FIG. 7 provides a schematic diagram of a ring modulator comprising anintegrated passive/active modulator unit, in accordance with an exampleembodiment;

FIG. 8 provides a schematic diagram of a cascaded ring modulatorcomprising an integrated passive/active modulator unit, in accordancewith an example embodiment.

FIG. 9 provides a schematic diagram of a parallel ring modulatorcomprising two integrated passive/active modulator units, in accordancewith an example embodiment.

FIG. 10 provides a flowchart illustrating various processes, procedures,and/or operations performed in fabricating an integrated passive/activemodulator unit, in accordance with an example embodiment.

FIGS. 11A-11E provide cross-sectional views of various stages offabricating an integrated passive/active modulator unit, in accordancewith an example embodiment.

FIG. 12 provides a block diagram of an example trapped ion quantumcomputer comprising an integrated passive/active modulator unit of anexample embodiment.

FIG. 13 provides a flowchart illustrating various processes, procedures,and/or operations performed in integrating an integrated passive/activemodulator unit with an ion trap of a trapped ion quantum computer, inaccordance with an example embodiment.

FIGS. 14A-14C provide cross-sectional views of various stages ofintegrating an integrated passive/active modulator unit with an ion trapof a trapped ion quantum computer, in accordance with an exampleembodiment.

FIG. 15 provides a schematic diagram of an example controller of aquantum computer comprising an ion trap apparatus, in accordance with anexample embodiment.

FIG. 16 provides a schematic diagram of an example computing entity of aquantum computer system that may be used in accordance with an exampleembodiment.

DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, the invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. The term “or” (also denoted “/”) is used herein in boththe alternative and conjunctive sense, unless otherwise indicated. Theterms “illustrative” and “exemplary” are used to be examples with noindication of quality level. The terms “generally” and “approximately”refer to within engineering and/or manufacturing limits and/or withinuser measurement capabilities, unless otherwise indicated. Like numbersrefer to like elements throughout.

In various scenarios, it may be desired to provide a photonic beam thatis modulated such that the intensity of the beams is rapidly switchedbetween an on/high intensity and an off/low intensity. For example, thephotonic beam may be provided to a target. Provision of such a photonicbeam is often accomplished using free space optics and free space AOMs.In an example embodiment, the target is a qubit of a quantum computer.For example, the target may be an ion trapped in an ion trap (e.g., of atrapped ion quantum computer) and the photonic beam may be used toionize an atom being loaded into the ion trap, initialize an ion withinthe ion trap into a known quantum state, perform a quantum logic gate onan ion within the ion trap, perform cooling of an ion within the iontrap, re-pump an ion within the ion trap, and/or the like.

In various scenarios, these free space optics and free space AOMs may bereplaced with various embodiments of integrated passive/activemodulators. In various embodiments, the use of integrated passive/activemodulators may reduce the physical space required to house the opticalequipment providing the optical paths for the photonic beams to bedelivered to the target. This may permit the loading of more targetsinto a target space. For example, use of the integrated passive/activemodulators of various embodiments may enable additional ions to beloaded into the ion trap.

In various embodiments, the photonic beams are high powered beams andthe integrated passive/active modulators are configured to provide thebeams with very low loss. In various embodiments, the integratedpassive/active modulators are configured to provide a large ratiobetween the on/high intensity state and the off/low intensity state ofthe provided photonic beam. In various embodiments, the integratedpassive/active modulators are configured to modulate the intensity ofthe photonic beam rapidly. In various embodiments, the integratedpassive/active modulators are configured to modulate photonic beamscharacterized by visible and/or UV wavelengths.

FIG. 1 illustrates an example embodiment of a passive/active modulatorunit 100 (referred to herein as a unit 100). In various embodiments, aunit 100 comprises an upstream passive portion 110B, an active portion150, and a downstream passive portion 110A. In various embodiments, theupstream passive portion 110B is configured for delivering an inputphotonic beam 2 to an active portion 150. The active portion 150receives electrical signal 4, which causes the active portion 150 tomodulate the input photonic beam 2 to provide a modulated outputphotonic beam 6. The downstream passive portion 110A provides the outputphotonic beam 6 to a target or additional downstream optics. In variousembodiments, the active portion is tapered in at least one of theupstream or downstream directions. For example, an upstream taper and/ora downstream taper of the active portion 150 may act as an opticalinterface between the passive waveguide of the passive portions 110 andthe active waveguide of the active portion 150. The photon beams areshown in FIGS. 1 and 5-9 as dashed lines.

FIG. 2 provides a perspective view of an example unit 100. FIG. 3provides a cross-sectional view of the unit 100 taken at line AA of FIG.2 and FIG. 4 provides a cross-sectional view of the unit taken at lineBB of FIG. 2. For example, FIG. 3 provides a cross-sectional view of apassive portion 110 (e.g., 110A, 110B) and FIG. 4 provides across-sectional view of an active portion 150. In various embodiments,the cross-sectional views shown in FIGS. 3 and 4 are taken in planessubstantially perpendicular to the unit axis 105. In variousembodiments, the unit 100 comprises a substrate 112 upon which thevarious elements of the unit 100 are fabricated. A first cladding layer114 is disposed and/or deposited on the substrate 112. For example, thefirst cladding layer 114 may be directly disposed on the substrate 112.For example, the first cladding layer 114 may be an oxide and/ordielectric layer. For example, the first cladding layer 114 may be madeof SiO₂, in an example embodiment.

In various embodiments, the first cladding layer 114 is sandwichedbetween the passive waveguide 116 and the substrate 112. In variousembodiments, the passive waveguide 116 is disposed and/or deposited onthe first cladding layer 114. In various embodiments, the passivewaveguide 116 is made of Al₂O₃, Si₃N₄, HfO₂, AlN, and/or Ta₂O₅. As shownin FIG. 3, the passive waveguide 116 has a width w_(p) in a directionsubstantially perpendicular to the unit axis 105 and substantiallyparallel to the surface 111 of the substrate 112 and a thickness t_(p)in a direction substantially perpendicular to both the unit axis 105 andthe surface 111 of the substrate 112. In various embodiments, thepassive waveguide 116 is made of a material having a refractive indexthat allows for propagation of a photonic beam through the passivewaveguide 116 with only a small amount of loss (e.g., via dissipationand/or leakage). In various embodiments, the waveguide 116 may define aunit axis 105 such that a photonic beam (e.g., input photonic beam 2and/or output photonic beam 6) travels through the unit 100 in adirection substantially parallel to the unit axis 105.

In various embodiments, a second cladding layer 118 is disposed and/ordeposited partially on the passive waveguide 116 and partially on thefirst cladding layer 114. For example, the second cladding layer 118 andfirst cladding layer 114 may enclose passive waveguide 116 in directionsradially extending from the unit axis 105. The first and second claddinglayers 114, 118 have a width W in a direction substantiallyperpendicular to the unit axis 105 and the substantially parallel to thesurface 111 of the substrate 112. In various embodiments, the widthw_(p) is smaller than the width W of the second cladding layer 118 andthe first cladding layer 114 such that the passive waveguide 116 isenclosed by the first and second cladding layers 114, 118 in directionsradial to the unit axis 105. In various embodiments, the second claddinglayer 118 is an oxide and/or dielectric layer. For example, the secondcladding layer 118 may be made of SiO₂, in an example embodiment.

In various embodiments, the passive portions 110A, 110B of unit 100 donot comprise any active components. In various embodiments, the activeportion 150 comprises active components configured to cause modulationof a photon beam passing through the active portion 150. As shown inFIG. 4, the active portion 150 comprises the substrate 112, the firstcladding layer 114, the passive waveguide 116, and the second claddinglayer 118. In various embodiments, the substrate 112, the first claddinglayer 114, the passive waveguide 116, and the second cladding layer 118are continuous from the upstream passive portion 110B, active portion150, and the downstream passive portion 110A. For example, a photon beampassing through the upstream passive portion 110B to the active portion150 will not experience a seam in the passive waveguide 116 materialand/or first and/or second cladding layers 114, 118 between the upstreampassive portion 110B and the active portion 150. Similarly, a photonbeam passing from the active portion 150 to the downstream passiveportion 110A will not experience a seam in the passive waveguide 116material and/or first and/or second cladding layers 114, 118 between theactive portion 150 and the downstream passive portion 110A.

In various embodiments, the active portion 150 further comprises activewaveguide 156. In various embodiments, the active waveguide 156 isdisposed and/or deposited on the second cladding layer 118. For example,the active waveguide 156 may disposed and/or deposited directly onto thesecond cladding layer 118. In various embodiments, the active waveguide156 is made of a material that, when an electrical signal is appliedthereto, the refractive index thereof changes. For example, in variousembodiments, the active waveguide 156 is made of LiNbO₃, LiTaO₃, orBaTiO₃. As shown in FIG. 4, the active waveguide 156 has a primaryactive waveguide width w_(a) in a direction substantially perpendicularto the unit axis 105 and substantially parallel to the surface 111 ofthe substrate 112 and a thickness t_(a) in a direction substantiallyperpendicular to both the unit axis 105 and the surface 111 of thesubstrate 112. The active waveguide 156 and the passive waveguide 116are separated by a separation distance s. In various embodiments, theseparation distance s is measured in a direction substantiallyperpendicular to both the unit axis 105 and the surface 111 of thesubstrate 112. In various embodiments, the separation distance s is thethickness of the layer of the second cladding layer 118 between thepassive waveguide 116 and the active waveguide 156.

In various embodiments, a third cladding layer 158 is disposed and/ordeposited on the active waveguide 156. In an example embodiment, theprimary active waveguide width w_(a) of the active waveguide 156, atleast along a portion of the length (e.g., in a direction substantiallyparallel to the unit axis 105) of the action portion 150, is less thanthe width W of the first, second, and third cladding layers 114, 118,158 and the third cladding layer 158 is disposed and/or deposited on theactive waveguide 156 and the second cladding layer 118. In variousembodiments, the third cladding layer 158 is an oxide and/or dielectriclayer. For example, the third cladding layer 158 may be made of SiO₂, inan example embodiment.

In various embodiments, the unit 100 further comprises electricalcontacts 154. For example, via openings may be etched into the thirdcladding layer 158 and electrical contacts 154 may be deposited into thevia openings. For example, the electrical contacts 154 may be inelectrical communication with the active waveguide 156. For example, anelectrical signal 4 may be applied to the electrical contacts 154 tocause the refractive index of the active waveguide 156 to change inresponse to the electrical signal 4. In various embodiments, theelectrical contacts 154 are made of a conductive material such ascopper, gold, silver, and/or the like.

The refractive index n of a material is defined as n≡c/v, where c is thespeed of light in a vacuum and v is the phase velocity of light in thematerial. The phase velocity v is the rate at which the phase of thelight evolves within the material. Thus, the phase of a photonic beamevolves differently when traveling through a material with a firstrefractive index compared to when traveling through a material with asecond refractive index, where the first and second refractive indicesare different from one another. Thus, by applying an electrical signal 4to the active waveguide 156 (e.g., via the electrical contacts 154), therefractive index of the active waveguide 156 may be changed which causesthe phase evolution of a photon beam propagating therethrough to change.

In various embodiments, the length of the active portion 150 is known.For example, the downstream taper length l_(e1), upstream taper lengthl_(e2), and central region taper length l_(a) may be known from themanufacturing and/or fabrication process. In various embodiments, thedownstream taper length l_(e1), upstream taper length l_(e2), andcentral region taper length l_(a) are known to a high level of accuracyfrom the design, manufacturing, and/or fabrication processes. Thevoltage of the electrical signal 4 applied to the active waveguide 156via the electrical contacts 154 may be controlled to cause the desiredamount of phase shifting of an input photon beam 2 to provide an outputbeam 6 having the desired phase shift. In various embodiments, thecontrol of the voltage of the electrical signal 4 is informed by theknowledge of the downstream taper length l_(e1), upstream taper lengthl_(e2), and/or central region taper length l_(a).

In various embodiments, an input photon beam 2 may be coupled into thepassive waveguide 116 of the upstream passive portion 110B of a unit100. In various embodiments, the input photon beam 2 may be a continuouswave laser and/or other photon beam source. The phase of the inputphoton beam 2 will evolve as the input photon beam 2 propagates throughthe passive waveguide 116 to the upstream taper 152B in accordance withthe approximately constant refractive index of the passive waveguide116. The input photon beam 2 is then coupled into the active waveguide156 of the active portion 150 via the upstream taper 152B. Therefractive index of the active waveguide 156 is controlled via theelectrical signal 4 that is biasing the active waveguide 156 (e.g., viathe electrical contacts 154). The phase of a photon beam propagatingthrough the active waveguide 156 will evolve based on the refractiveindex the photon beam experiences therein. The phase of the output beam6 may be different from an expected phase, where the expected phase isthe phase the first input photon beam 2 would have if the first inputphoton beam had continued to propagate through the active region 150without experiencing any phase evolution adjustment, modification,and/or change. For example, the electrical signal 4 may be used tocontrol the amount of difference in phase between the input photon beam2 and an output photon beam 6 and the how that amount of differenceevolves over time. An output photon beam 6 is coupled into the passivewaveguide 116 of the downstream passive portion 110A via the downstreamtaper 152A. The phase of the output photon beam 6 may then evolve as theoutput photon beam 6 propagates through the passive waveguide 116 of thedownstream passive portion 110A in accordance with the approximatelyconstant refractive index of the passive waveguide 116. The outputphoton beam 6 may then be coupled to another waveguide (e.g., 210, 410)or delivered to a target via the passive waveguide 116 of the downstreampassive portion 110A.

In various embodiments, the input photon beam 2 and/or the output photonbeam 6 may be a high power photon beam. For example, the input photonbeam 2 and/or the output photon beam 6 (e.g., in a high intensity/onstate) may have a power of 100 mW or greater.

In various embodiments, the active portion 150 comprises an upstreamtaper 152B and a downstream taper 152A. For example, at the downstreamend 164 of the active portion 150, the active waveguide 156 has adownstream taper end width w_(e1) that is less than the primary activewaveguide width w_(a) (e.g., the width of the active waveguide 156 inthe central region 166 of the active portion 150). For example, at theupstream end 162 of the active portion 150, the active waveguide 156 hasa width w_(e2) that is less than the primary active waveguide widthw_(a) (e.g., the width of the active waveguide 156 in the central region166 of the active portion 150). As the active portion 150 extends fromthe downstream end 164 to a downstream edge of the central region 166along the unit axis 105, the width of the active waveguide 156 increasesfrom the downstream taper end width w_(e1) to the primary activewaveguide width w_(a). Along the central region 166 (e.g., between thedownstream edge of the central region and the upstream edge of thecentral region) of the active portion 150, the width of the activewaveguide 156 is maintained at the primary active waveguide width w_(a).As the active waveguide 156 extends from the upstream edge of thecentral region 166 to the upstream end 162 of the active portion 150,the width of the active waveguide 156 tapers and/or decreases fromprimary active waveguide width w_(a) to the downstream taper end widthw_(e2). In an example embodiment, the downstream taper end width w_(e1)and the upstream taper end width w_(e2) are approximately equal.

In various embodiments, the upstream taper 152B and the downstream taper152A acts as optical interfaces between the passive waveguide 116 andthe active waveguide 156. For example, the upstream taper 152B mayoptically couple and/or act as an optical interface between the passivewaveguide 116 of the upstream passive portion 110B to the activewaveguide 156 of the active portion 150. For example, the downstreamtaper 152A may optically couple and/or act as an optical interfacebetween the active waveguide 156 of the active portion 150 and thepassive waveguide 116 of the downstream passive portion 110A. In variousembodiments, the geometry of the upstream and downstream tapers 152A,152B are optimized to achieve high efficiency transmission between thepassive portions 110A, 110B and the active portion 150. For example, thegeometry of the upstream and downstream tapers 152A, 152B may beoptimized to achieve approximately the highest efficiency transmissionbetween the passive portions 110A, 110B and the active portion. Forexample, the geometry of the upstream and downstream tapers 152A, 152Bmay be tailored based on the wavelength or wavelength band of anintended application, a mode or desired mode of light for the intendedapplication, operating conditions (e.g., temperature, pressure, etc.)expected for the intended application, and/or the like. In variousembodiments, tailoring the geometry includes setting the downstreamtaper length l_(e1), upstream taper length l_(e2), downstream tip widthw_(e1), upstream tip width w_(e2), and a taper profile along the lengthof each taper 152. For example, a taper 152 may have a linear profile,as shown in FIG. 1, an exponential profile, quadratically, cosine-likeprofile, and/or the like as appropriate for the intended application ofthe unit 100.

In various embodiments, as can be seen in FIG. 4, the passive waveguide116 may continue through the active portion 150 of the unit 100. In anexample embodiment, the width of the passive waveguide 116 is maintainedat width w_(p) through the active portion 150. In an example embodiment,the width of the passive waveguide 116 may be narrower than width w_(p)through at least a portion of the active portion 150. For example, thewidth of the passive waveguide 116 may decrease (e.g., linearly,quadratically, exponentially, cosine-like, and/or the like) between theupstream end 162 of the active portion 150 and the upstream edge of thecentral region 166, the width of the passive waveguide 116 may beconstant through the central region 166 of the active portion (e.g., ata width that is less than width w_(p)), and the width of the passivewaveguide 116 may increase (e.g., linearly, quadratically exponentially,cosine-like, and/or the like) between the downstream edge of the activeportion 150 and the downstream end 164 of the active portion 150 suchthat at the downstream end 164 of the active portion 150 the width ofthe passive waveguide 116 is width w_(p). In an example embodiment, thewidth of the passive waveguide 116 may be wider in the central region166 of the active portion 150 than in the passive portions 110A, 110B.

In various embodiments the width of the passive waveguide w_(p) and/orthe width of the active waveguide w_(a) is/are configured to enable theunit 100 to be able to transmit and/or modulate high power visibleand/or UV photonic beams. For example, the passive waveguide 116 may bepatterned and/or formed such that the passive waveguide has across-sectional area (e.g., in a cross-section taken substantiallyperpendicular to a unit axis 105 of the unit 100) that is configuredsuch that when a photonic beam characterized by a wavelength in a rangeof approximately 350-1000 nm and having an appropriate power for anintended application propagates through the passive waveguide 116, theintensity of the photonic beam in a unit area of the passive waveguide116 is less than a damage threshold intensity for the material of thepassive waveguide 116. Similarly, the central region 166 of the activewaveguide 156 may be patterned and/or formed such that the activewaveguide 156 has a cross-sectional area (e.g., in a cross-section takensubstantially perpendicular to a unit axis 105 of the unit 100) that isconfigured such that when a photonic beam characterized by a wavelengthin a range of approximately 350-1000 nm and having an appropriate powerfor an intended application propagates through the central region 166 ofthe active waveguide 156 the intensity of the photonic beam in a unitarea of the passive waveguide 156 is less than a damage thresholdintensity for the material of the passive waveguide 156. In an exampleembodiment, the appropriate power for the intended application is in therange of approximately 100-300 mW.

In various embodiments, the upstream taper 152B may be configured tooptically mate the passive waveguide 116 of the upstream passive portion110B to the active waveguide 156 of the active portion 150 with lowtransition loss. In various embodiments, the downstream taper 152A maybe configured to optically mate the active waveguide 156 of the activeportion 150 to the passive waveguide 116 of the downstream passiveportion 110A with low transition loss. In various embodiments, thepassive waveguide 116 is made of a material with low loss. For example,the intensity of a beam propagating through the passive waveguide 116 isapproximately constant and/or is only slightly reduced (e.g., by up to afew percent and/or the like) over a length of the passive waveguide 116.In various embodiments, the active waveguide 156 may be made of amaterial with a higher loss than the passive waveguide 116 material.However, as a beam propagating through the unit 100 only interacts withthe active waveguide 156 for a portion of the length of the unit 100,the overall loss in intensity of a beam propagating through the unit 100is low (e.g., up to a few percent).

The extent of the optical confinement within either the passive oractive waveguides 116, 156 can be controlled through choice of materialof the passive waveguide 116 and its associated refractive index, widthw_(p) and thickness t_(p) of the passive waveguide 116, separation sbetween the passive waveguide 116 and active waveguide 156, choice ofthe material of the active waveguide 156 and its associated refractiveindex, primary active waveguide width w_(a) and thickness t_(a) of theactive waveguide 156, and/or the like.

In various embodiments, the unit 100 and/or a modulator comprising oneor more units 100 (e.g., an MZI modulator 200, cascaded MZI modulator300, ring modulator 400, cascaded ring modulator 500, parallel ringmodulator 600, and/or the like) may be configured to change the phaseand/or modulate visible and/or ultra-violet (UV) light (e.g., lightcharacterized by wavelengths in the range of approximately 350-1000 nm).For example, because the active portion 150 is a relatively smallportion of the unit 100 (e.g., less than half the beam path through theunit 100) and/or due to the use of the downstream and/or upstream tapers152A, 152B, the unit 100 may cause phase changes and/or modulate a UVbeam without incurring damage. For example, the upstream taper 152B maybe designed to control how the mode of the input beam 2 is coupled intothe active waveguide 156 from the upstream portion 110A (e.g., thepassive waveguide 116) and the downstream taper 152A may be designed tocontrol how the mode of the output beam 6 is coupled out of the activewaveguide 156 and into the downstream portion 110B (e.g., the passivewaveguide 116). For example, the geometry of the active portion 150(e.g., the geometry of the active waveguide 156) may enable the unit 100to repeatedly be used to change the phase of a UV beam and/or enable amodulator comprising one or more units 100 to be used to repeatedlymodulate a UV beam. In various embodiments, the material used to formthe active waveguide 156 may be chosen based on its ability to have highpowered UV beams propagate therethrough.

Exemplary Modulators Comprising at Least One Integrated Active/PassiveModulator Unit

In various embodiments, one or more units 100 may be incorporated into amodulator. In various embodiments, the modulator is configured to switchbetween a high intensity/on state and a low intensity/off state at afrequency of at least approximately 100 MHz. In various embodiments, themodulator may provide a combined output beam with extinction ratiobetween the high intensity/on state to the low intensity/off state ofthe combined output beam of at least approximately 40 dB. In variousembodiments, the modulator may be configured to receive, modulate,and/or provide photon beams in the wavelength range of approximately350-1000 nm. In various embodiments, the modulator may be a low lossmodulator configured to receive, modulate, and/or provide photon beamsthat (when the modulated beam is in the high intensity/on state) has apower of at least approximately 100 mW.

In various embodiments, the modulator may combine at least one unit 100,an additional passive waveguide, and at least one beam splitter and/orbeam combiner. For example, the modulator may be configured to receive aprimary input beam (e.g., an visible and/or UV laser beam and/or thelike) coupled into at least a portion of the additional passivewaveguide; split the primary input beam into at least two parts (e.g.,first and second input beams 2 to be provided to two different units100, an input beam 2 to be provided to a unit 100 and an interactionbeam to be interacted with an output beam 6, and/or the like); providethe input beam(s) 2 to the active portion(s) 150 of the units(s) 100 viathe upstream passive portion(s) 110B; modify, adjust, change, and/or thelike the phase of the input beam(s) 2 based on biasing of the activewaveguide(s) 156 by electrical signal(s) 4 to provide output beam(s) 6;and interact two output beams 6 and/or an output beam 6 and aninteraction beam to generate a combined beam. The interaction of the twooutput beams 6 and/or the output beam 6 and the interaction beam willresult in either constructive or destructive interference between theinteracted beams based on the relative phase difference between theinteracted beams. When the interacted beams provide a combined outputbeam through constructive interference, the combined output beam will bein the high intensity/on state. When the interacted beams provide acombined output beam through destructive interference, the combinedoutput beam will be in the low intensity/off state. The combined outputbeam may be coupled into at least a portion of the additional passivewaveguide and provided (e.g., via the additional passive waveguide) to adownstream optical component, a target, and/or the like.

In various embodiments, the modulator comprising at least one integratedactive/passive modulator unit may take a variety of forms. Some exampleforms discussed in more detail below include MZI modulators and ringmodulators. For example, an MZI modulator may comprise one or more pairsof units 100, such as in the example MZI modulator 200 and cascaded MZImodulator 300 illustrated in FIGS. 5 and 6, respectively. In anotherexample, a ring modulator may comprise at least one unit 100 that hasbeen formed into a ring or loop, such as in the example ring modulator300, cascaded ring modulator 400, and parallel ring modulator 500illustrated in FIGS. 7, 8, and 9, respectively.

Some Exemplary Mach-Zehnder Interferometer Modulators

FIG. 5 illustrates an example MZI modulator 200. In various embodiments,the MZI modulator 200 comprises a first unit 100A and a second unit100B. In various embodiments, the MZI modulator 200 comprises a firstunit 100A and a second unit 100B that are in parallel within oneanother. Each of the first and second units 100A and 110B comprise anactive portion 150 (e.g., 150A, 150B) sandwiched between a passiveupstream portion 110B and a passive downstream portion 110A.

The first unit 100A comprises a first active portion 150A that isconfigured to receive and react to a first electrical signal 4A. Forexample, the refractive index of the active waveguide 156 of the activeportion 150A of the first unit 100A may change in response to changes inthe first electrical signal 4A applied to the electrical contacts 154 ofthe first unit 100A. The second unit 100B comprises a second activeportion 150B that is configured to receive and react to a secondelectrical signal 4B. For example, the refractive index of the activewaveguide 156 of the active portion 150B of the second unit 100B maychange in response to changes in the second electrical signal 4B appliedto the electrical contacts 154 of the second unit 100B.

In various embodiments, the MZI modulator 200 comprises an upstreampassive waveguide 210B that is coupled to the passive upstream portions110B of both the first and second units 100A, 100B. For example, theupstream passive waveguide 210B may be a passive waveguide that iscoupled to the passive upstream portion 110B of each of the first unit100A and the second unit 100B. In an example embodiment, the upstreampassive waveguide 210B is coupled to the passive upstream portions 110Bof the first and second units 100A, 100B via a beam splitter 202. Thefirst and second units 100A, 100B may be integrated passive/activemodulator units 100 comprising a passive upstream portion 110B, anactive portion 150, and a passive downstream portion 110A. The MZImodulator 200 may further comprise a downstream passive waveguide 210A.The downstream passive waveguide 210A may be coupled to the downstreampassive portion 110A of each of the first and second units 100A, 100B.For example, the downstream passive waveguide 210A may be coupled to thedownstream passive portion 110A of the first and second units 100A, 100Bvia a beam combiner 204.

For example, a primary input beam 3 may be provided to the upstreampassive waveguide 210B. A beam splitter 202 may be used to split theprimary input beam 3 traveling through the upstream passive waveguide210B into a first input photon beam 2A and a second input photon beam2B. In an example embodiment, the first input photon beam 2A hasapproximately half the intensity of the primary photon beam 3 (e.g.,40-60% of the intensity of primary photon beam 3). The first inputphoton beam 2A may be provided to and/or propagate through the passiveupstream portion 110B of the first unit 100A and thereby be provided toand/or propagate through the active portion 150A of the first unit 100A.The phase of the first input photon beam 2A may be modified, changed,adjusted, and/or the like as the first input photon beam 2A propagatesthrough the active portion 150A based on a first electrical signal 4Aprovided to the electrical contacts 154 of the active portion 150A ofthe first unit such that a first output beam 6A is provided to and/orpropagates through the passive downstream portion 110A of the first unit100A. Similarly, the second input photon beam 2B may be provided toand/or propagate through the passive upstream portion 110B of the secondunit 100B and thereby be provided to and/or propagate through the activeportion 150B of the second unit 100B. The phase of the second inputphoton beam 2B may be modified, changed, adjusted, and/or the like asthe second input photon beam 2B propagates through the active portion150B based on a second electrical signal 4B provided to the electricalcontacts 154 of the active portion 150B of the second unit 100B suchthat a second output beam 6B is provided to and/or propagates throughthe passive downstream portion 110A of the second unit 100B. The passivedownstream portions 110A of both the first unit 100A and the second unit100B may be coupled to a beam combiner 204 that receives the first andsecond output beams 6A, 6B, couples and/or combines the first and secondoutput beams 6A, 6B to form a combined output beam 7, and provides thecombined output beam 7 to a downstream passive waveguide 210A.

Based on the phase difference between the first and second output beams6A and 6B, combining the first and second output beams (e.g., via thebeam combiner 204) may result constructive interference or destructiveinterference. If the first and second output beams 6A, 6B are aligned inphase (e.g., the relative phase difference of the two beams isapproximately zero and/or both beams experienced approximately the samechange in phase when propagating through the active portions 150A, 150Bof the respective first and second units 100A, 100B), the first andsecond output beams 6A, 6B will experience constructive interference andthe combined output beam 7 will have approximately the same intensity asthe primary input beam 3 (minus any loss). If the first and secondoutput beams 6A, 6B are out of phase, the first and second output beams6A, 6B will experience destructive interference and the combined outputbeam 7 will have a significantly lower intensity compared to the primaryinput beam 3 (even after taken into account any loss). For example, ifthe active region 150A of the first unit 100A causes the first inputphoton beam 2A to experience relative phase change that is notapproximately and integer multiple of π with respect to the phase shiftexperienced by the second input photon beam 2B when propagating throughthe active region 150B of the second unit 100B, the first and secondoutput beams 6A, 6B will be out of phase and will destructivelyinterfere to provide a combined output beam 7 having a reducedintensity. If the relative phase shifts of first and second output beamsare π/2 or 3π/2, the combined output beam 7 will have an intensity ofapproximately zero.

In various embodiments, the first and second electrical signals 4A, 4Bmay be controlled (e.g., via a computing entity, controller, and/or thelike) to cause the combined output beam 7 to be modulated between a highintensity state and a low intensity state. For example, the ratio of theintensity of the combined output beam 7 to a corresponding inputphotonic beam 3 for the high intensity state may be large (e.g.,approximately 1, greater than 0.95, greater than 0.9, greater than 0.8,greater than 0.7, greater than 0.6, and/or the like). The ratio of theintensity of the combined output beam 7 to a corresponding inputphotonic beam 3 for the low intensity state may be small (e.g., lessthan 0.5, less than 0.4, less than 0.3, less than 0.2, less than 0.1,less than 0.05, approximately 0, and/or the like). For example, the highintensity state may be an “on” state and the low intensity state may bean “off” state. For example, the extinction ratio between the highintensity/on state to the low intensity/off state of the combined outputbeam 7 may be approximately 40 dB or greater. The material of the activewaveguides 156 of the first and second units 100A, 100B may reactquickly to changes in the first and second electrical signals 4A,4Bapplied thereto, respectively. Thus, the MZI modulator 200 may beswitched between a high intensity/on state and a low intensity/off statequickly (e.g., at a frequency of approximately 100 MHz or faster).

In various embodiments, the beam splitter 202 and/or the beam combiner204 are low loss optical components. In various embodiments, the beamsplitter 202 and/or the beam combiner 204 may be active or passiveoptical components, as appropriate for the application. In an exampleembodiment, the beam splitter 202 may be the upstream passive waveguide210B splitting into the two upstream passive portions 110B of the firstand second units 100A, 100B. In an example embodiment, the beam combiner204 may be the two downstream passive portions 110A combining into onedownstream passive waveguide 210A.

In various embodiments, the first and second units 100A, 100B haveupstream passive portions 110B that are the same length, active portions150 that are the same length, and downstream passive portions 110A thatare the same length and/or have lengths that differ by a particularlength, wherein the particular length is the product of a wavelength λthat characterizes the input photonic beam 3 and an integer (e.g., nλ,where n is an integer). For example, in an example embodiment, any phasedifference between the first and second output beams 6A, 6B is due tophase changes, alterations, modifications, and/or the like experiencedby the first and/or second input photonic beam portions 2A, 2B whenpropagating through the respective action region 150A, 150B. In anexample embodiment, one or both of the downstream or upstream passiveportions 110A, 110B of the first and second units 100A, 100B may bedifferent lengths. For example, the downstream passive portion 110A ofthe first unit 100A may be half a wavelength (e.g., λ/2) longer than thedownstream passive portion 110A of the second unit 100B. For example,the relative lengths of the downstream and/or upstream passive portions110A, 110B and/or the active portions 150A, 150B may be set so as tointroduce a relative phase shift between a first photonic beam passingthrough the first unit 100A and a second photonic beam passing throughthe second unit 100B.

FIG. 6 illustrates an example embodiment of a cascaded MZI modulator300. In various embodiments, the cascaded MZI modulator 300 comprises atleast two MZI modulators 200 (e.g., 200A, 200B) that are seriallycoupled via an intermediate passive waveguide 210C. For example, thecascaded MZI modulator 300 comprises a first MZI modulator 200A and asecond MZI modulator 200B. The first MZI modulator 200A comprises firstand second units 100A, 100B with the upstream passive portions 110B ofthe first and second units 100A, 100B both coupled to an upstreampassive waveguide 210A (e.g., via a beam splitter 202 and/or the like)and the downstream passive portions 110A of the first and second units100A, 100B both coupled to the intermediate passive waveguide 210C(e.g., via a beam combiner 204 and/or the like). The second MZImodulator 200B comprises third and fourth units 100C, 100D with theupstream passive portions 110B of the third and fourth units 100C, 100Dboth coupled to the intermediate passive waveguide 210C (e.g., via abeam splitter 202 and/or the like). The downstream passive portions 110Aof both the third and fourth units 100C, 100D are both coupled to eitheranother intermediate passive waveguide 210C (e.g., if the cascaded MZImodulator comprises three or more MZI modulators 200) or to a downstreampassive waveguide 210A (e.g., if the second MZI modulator 200B is thelast MZI modulator 200 of the cascaded MZI modulator 300).

In various embodiments, a cascaded MZI modulator 300 may be used tofurther decrease the ratio of the intensity of the combined output beam7 compared to the intensity of the primary input beam 3 in the lowintensity/off state. For example, the first MZI modulator 200A may beoperated (e.g., via the first and second electrical signals 4A, 4Bapplied to the active portions 150A, 150B of the first and second units100A, 100B, respectively) in a low intensity/off state to provide anintermediate beam 5 to the intermediate passive waveguide 210C that hasa low intensity compared to the primary input beam 3 (e.g., the ratio ofthe intensity of the intermediate beam to the intensity of the inputphotonic beam may be less than 0.5, less than 0.4, less than 0.3, lessthan 0.2, less than 0.1, less than 0.05, approximately 0, and/or thelike). The intermediate passive waveguide 210C may then provide theintermediate beam 5 to the second MZI modulator 200B. The second MZImodulator 200B may then be operated (e.g., via the third and fourthelectrical signals 4C, 4D applied to the active portions 150C, 150D ofthe third and fourth units 100C, 100D, respectively) in a lowintensity/off state to provide a combined output beam 7 to thedownstream passive waveguide 210A that has a low intensity compared tothe intermediate beam 5 (e.g., the ratio of the intensity of thecombined output beam to the intensity of the intermediate beam may beless than 0.5, less than 0.4, less than 0.3, less than 0.2, less than0.1, less than 0.05, approximately 0, and/or the like). Thus, the ratioof the intensity of the combined output beam 7 to the primary input beam3 may be less than 0.25, less than 0.16, less than 0.09, less than 0.04,less than 0.01, less than 0.025, approximately 0, and/or the like.

In various embodiments, a cascaded MZI modulator 300 may be used tofurther decrease the ratio of the intensity of the combined output beam7 compared to the intensity of the primary input beam 3 in the lowintensity/off state while having a minimal effect on the ratio of theintensity of the combined output beam 7 compared to the intensity of theprimary input beam 3 in the high intensity/on state (e.g., due to thelow loss nature of the units 100). For example, the extinction ratiobetween the high intensity/on state to the low intensity/off state ofthe combined output beam 7 may be approximately 40 dB or greater. Invarious embodiments, the cascaded MZI modulator 300 may be switchedbetween a high intensity/on state and a low intensity/off state quickly(e.g., at a frequency of approximately 100 MHz or faster).

Some Exemplary Ring Modulators

FIG. 7 illustrates an example embodiment of ring modulator 400, inaccordance with an example embodiment. In various embodiments, the ringmodulator 400 comprises a unit ring or loop 405. In various embodiments,a unit ring or loop 405 is a unit 100 that is formed in a ring or loop.In various embodiments, the ring modulator 400 further comprises apassive waveguide 410. In various embodiments, the passive waveguide 410is a through passive waveguide that may be used to couple the modulatorto other waveguide portions, other optical components, and/or the like.For example, the unit ring or loop 405 may comprise a unit 100 formed ina ring or loop such that the upstream passive waveguide 110A and thedownstream passive waveguide 110B are both in photonic communicationwith and/or optically coupled to the passive waveguide 410. In anexample embodiment, the unit ring or loop 405 is optically coupled tothe passive waveguide via a beam splitter/combiner 402.

In an example embodiment, a primary input beam 3 propagates through thepassive waveguide 410. The primary input beam 3 propagating through thepassive waveguide 410 interacts with a beam splitter/combiner 402. Thebeam splitter/combiner 402 causes the primary input beam 3 to be splitinto an input photon beam 2 and an interaction beam. The input photonbeam 2 is provided to the unit ring or loop 405 (e.g., via the beamsplitter/combiner 402). For example, the input photon beam 2 may beprovided to an upstream passive portion 110B of the unit 100. The beamsplitter/combiner 402 may cause the second input photon beam tointerfere with an output beam 6 that has passed through the activeportion 150 of the unit 100. For example, the input photon beam 2 may beprovided to the active portion 150 (e.g., via the upstream taper 152B)wherein the evolution of the phase of the input photon beam 2 may bemodified, adjusted, and/or changed such that an output beam 6 isprovided to the downstream passive portion 110A (e.g., via thedownstream taper 152B). The phase of the output beam 6 may be differentfrom an expected phase, where the expected phase is the phase the inputphoton beam 2 would have if the first input photon beam had continued topropagate through the active region 150 without experiencing any orsubstantially any phase evolution adjustment, modification, and/orchange. The output beam 6 may be provided to the beam splitter/combiner402 via the downstream passive portion 110A of the unit 100. The beamsplitter/combiner 402 combines and/or interferes the output beam 6 andthe interaction beam. The result of combining and/or interfering theinteraction beam with the output beam 6 is a combined output beam 7 thatpropagates through the passive waveguide 410 downstream from the beamsplitter/combiner 402. In an example embodiment, the input photon beam 2of the input has an intensity that is approximately half the intensity(e.g., 60-40% of the intensity) of the primary input beam 3.

In various embodiments, the active portion 150 of the unit 100 maymodify, adjust, change, and/or the like the phase of the input photonbeam 2 such that the output beam 6 has a phase that constructively ordestructively interferes with the second input photon beam. For example,an electrical signal 4 may be provided to the active portion 150 suchthat the phase of the input photon beam 2 is modified, adjusted, and/orchanged to provide an output beam 6 that has approximately the samephase as the second input photon beam to provide a combined output beam7 in a high intensity/on state. For example, an electrical signal 4 maybe provided to the active portion 150 such that the phase of the inputphoton beam 2 is modified, adjusted, and/or changed to provide an outputbeam 6 that is out of phase with respect to the second input photon beamto provide a combined output beam 7 in a low intensity/off state.

In various embodiments, the electrical signal 4 may be controlled (e.g.,via a computing entity, controller, and/or the like) to cause thecombined output beam 7 to be modulated between a high intensity/on stateand a low intensity/off state. For example, the ratio of the intensityof the combined output beam 7 to the intensity of a correspondingprimary input beam 3 for the high intensity/on state may be large (e.g.,approximately 1, greater than 0.95, greater than 0.9, greater than 0.8,greater than 0.7, greater than 0.6, and/or the like). The ratio of theintensity of the combined output beam 7 to the intensity of acorresponding input photonic beam 3 for the low intensity/off state maybe small (e.g., less than 0.5, less than 0.4, less than 0.3, less than0.2, less than 0.1, less than 0.05, approximately 0, and/or the like).For example, the extinction ratio between the high intensity/on state tothe low intensity/off state of the combined output beam 7 may beapproximately 40 dB or greater. The material of the active waveguide 156of the unit 100 may react quickly to changes in the electrical signal 4applied thereto. Thus, the ring modulator 400 may be switched between ahigh intensity/on state and a low intensity/off state quickly. Invarious embodiments, the ring modulator 400 may be switched between ahigh intensity/on state and a low intensity/off state quickly (e.g., ata frequency of approximately 100 MHz or faster).

In various embodiments, the beam splitter/combiner 402 is a low lossoptical component. In various embodiments, the beam splitter/combiner402 is a two optical component element and at least one of the opticalcomponents (e.g., a beam splitter or a beam combiner) is a low lossoptical component. In various embodiments, the beam splitter/combiner402 may be and/or comprise active or passive optical components, asappropriate for the application.

FIG. 8 illustrates an example embodiment of a cascaded ring modulator500. In various embodiments, a cascaded ring modulator 500 comprises apassive waveguide 410, a unit ring or loop 405, and a passive waveguidering or loop 505. In various embodiments, the passive waveguide 410 is athrough passive waveguide that may be used to couple the modulator toother waveguide portions, other optical components, and/or the like. Invarious embodiments, the passive waveguide ring or loop 505 may beconfigured to couple light into and out of the through passive waveguide410. In various embodiments, the cascaded ring modulator 500 comprises afirst and second beam splitter/combiner 502, 504. For example, a primaryinput beam 3 may be propagating through the passive waveguide 410 andinteract with the first beam splitter/combiner 502. The first beamsplitter/combiner 502 may split the primary input beam 3 into a firstinput beam 2′ and a first interaction beam. The first beamsplitter/combiner 502 may couple the first input beam 2′ into thepassive waveguide ring or loop 505. The first input beam 2′ maypropagate through the passive waveguide ring or loop 505 and interactwith a second beam splitter/combiner 504. The second beamsplitter/combiner 504 may split the first input beam 2′ into a secondinput beam 2 that is coupled into the unit ring or loop 405 and a secondinteraction beam that is interacted with an output beam 6 of the unitring or loop 405. The second input beam 2 propagates through theupstream passive portion 110B and interacts with the active portion 150of the unit 100. The active portion 150 may adjust, modify, change,and/or the like the phase of the second input beam 2 to generate theoutput beam 6. The output beam 6 propagates through the downstreampassive portion 110A of the unit 100. The output beam 6 interacts withthe second beam splitter/combiner 504 to cause the output beam 6 tointerfere with the second interaction beam, resulting in an intermediatecombined beam 6′ that propagates through the passive waveguide ring orloop 505. The intermediate combined beam 6′ may propagate through thewaveguide ring or loop 505 to interact with the first beamsplitter/combiner 502. The first beam splitter/combiner 502 causes thefirst interaction beam and the intermediate combined beam 6′ to interactto provide a combined output beam 7 propagating downstream through thepassive waveguide 410.

In various embodiment, an electrical signal 4 may be provided to theactive portion 150 (e.g., to the active waveguide 156 via contacts 154)to cause the output beam 7 to be in a high intensity/on state or a lowintensity/off state as a result of constructive and/or destructiveinterference between the intermediate combined beam 6′ and the firstinteraction beam. For example, the electrical signal 4 may be configuredto cause, for a first period of time, the phase of the second input beam2 to be changed, modified, and/or adjusted such that the resultingintermediate combined beam 6′ destructively interferes with the firstinteraction beam, to provide a combined output beam 7 in a lowintensity/off state. For example, the electrical signal 4 may beconfigured to cause, for a second period of time, the phase of thesecond input beam 2 to be changed, modified, and/or adjusted such thatthe resulting intermediate combined beam 6′ constructively interfereswith the first interaction beam, to provide a combined output beam 7 ina high intensity/on state.

In various embodiments, the first and second beam splitter/combiners502, 504 are low loss optical components. In various embodiments, thefirst and/or second beam splitter/combiners 502, 504 is a two opticalcomponent element and at least one of the optical components (e.g., abeam splitter or a beam combiner) is a low loss optical component. Invarious embodiments, the first and/or second beam splitter/combiners502, 504 may be and/or comprise active or passive optical components, asappropriate for the application.

The material of the active waveguide 156 of the unit 100 may reactquickly to changes in the electrical signal 4 applied thereto. Thus, thecascaded ring modulator 500 may be switched between a high intensity/onstate and a low intensity/off state quickly. In various embodiments, thecascaded ring modulator 500 may be switched between a high intensity/onstate and a low intensity/off state quickly (e.g., at a frequency ofapproximately 100 MHz or faster). In various embodiments, the extinctionratio between the high intensity/on state to the low intensity/off stateof the combined output beam 7 may be approximately 40 dB or greater.

FIG. 9 illustrates an example embodiment of a parallel ring modulator600. In various embodiments, a parallel ring modulator 600 comprises apassive waveguide 410, a first unit ring or loop 405A, and a second unitring or loop 405B. The first unit ring or loop 405A comprises a firstunit 100A and the second unit ring or loop 405B comprises a second unit100B. In various embodiments, the parallel ring modulator 600 comprisesa first beam splitter/combiner 602 configured to couple the first unitring or loop 405A to the passive waveguide 410. In various embodiments,the passive waveguide 410 is a through passive waveguide that may beused to couple the modulator to other waveguide portions, other opticalcomponents, and/or the like. In an example embodiment, the parallel ringmodulator 600 comprises a second beam splitter/combiner 604 configuredto couple the second unit ring or loop 405B to the passive waveguide410.

For example, a primary input beam 3 may be coupled into the passivewaveguide 410, propagate along the passive waveguide 410, and interactwith the first beam splitter/combiner 602. The first beamsplitter/combiner 602 may split the primary input beam 3 into a firstinput beam 2A and a first interaction beam. In an example embodiment,the intensity of the first input beam 2A is approximately half (e.g.,60-40%) of the intensity of the primary input beam 3. The first inputbeam 2A may be provided to the first unit ring or loop 405A such thatthe first input beam 2A propagates through the upstream passive portion110B and interacts with the active portion 150A of the first unit 100A.The active portion 150A of the first unit 100A may modify, adjust,change, and/or the like phase of the first input beam 2A to provide afirst output beam 6A. In various embodiments, the modification,adjustment, change, and/or the like to the phase of the first input beam2A by the active portion 150A (e.g., the amount of change and the timeevolution the phase change) is controlled via a first electrical signal4A applied to the active waveguide 156 of the active portion 150A. Thefirst output beam 6A propagates through the downstream passive portion110A of the first unit 100A and interacts with the first beamsplitter/combiner 602. The first beam splitter/combiner 602 combines thefirst output beam 6A and the first interaction beam. The first outputbeam 6A and the first interaction beam may constructively ordestructively interfere based on the relative phases thereof to generatean intermediate beam 5. The intermediate beam 5 continues to propagatealong the passive waveguide 410.

In various embodiments, as the intermediate beam 5 propagates along thepassive waveguide 410, the intermediate beam 5 interacts with a secondbeam splitter/combiner 604. The second beam splitter/combiner 604 maysplit the intermediate beam 5 into a second input portion 2B and asecond interaction beam. In an example embodiment, the intensity of thefirst input beam 2B is approximately half (e.g., 60-40%) of theintensity of the intermediate beam 5. The second input beam 2B may beprovided to the second unit ring or loop 405B such that the second inputbeam 2B propagates through the upstream passive portion 110B andinteracts with the active portion 150B of the second unit 100B. Theactive portion 150B of the second unit 100B may modify, adjust, change,and/or the like phase of the second input beam 2B to provide a secondoutput beam 6B. In various embodiments, the modification, adjustment,change, and/or the like to the phase of the second input beam 2B by theactive portion 150B (e.g., the amount of change and the time evolutionthe phase change) is controlled via a second electrical signal 4Bapplied to the active waveguide 156 of the active portion 150B. Thesecond output beam 6B propagates through the downstream passive portion110A of the second unit 100B and interacts with the second beamsplitter/combiner 604. The second beam splitter/combiner 604 combinesthe second output beam 6B and the second interaction beam. The secondoutput beam 6B and the second interaction beam may constructively ordestructively interfere based on the relative phases thereof to generatea combined output beam 7. The combined output beam 7 continues topropagate downstream along the passive waveguide 410.

In various embodiments, the combined output beam 7 may be in a highintensity/on state or a low intensity/off state and may switch betweenthese two states. The state of the combined output beam 7 and theswitching between the states of the combined output beam 7 controlledvia application of the first and second electrical signals 4A and 4B tothe first and second units 100A, 100B, respectively. For example, thefirst unit ring or loop 405A may be operated (e.g., via the firstelectrical signal 4 applied to the active portion 150A of the first unit100A) in a low intensity/off state to provide an intermediate beam 5 tothe that has a low intensity compared to the primary input beam 3 (e.g.,the ratio of the intensity of the intermediate beam to the intensity ofthe primary input beam may be less than 0.5, less than 0.4, less than0.3, less than 0.2, less than 0.1, less than 0.05, approximately 0,and/or the like). The second unit ring or loop 405B may then be operated(e.g., via the second electrical signal 4B applied to the active portion150B of the second unit 100B) in a low intensity/off state to provide acombined output beam 7 downstream to the passive waveguide 410 that hasa low intensity compared to the intermediate beam 5 (e.g., the ratio ofthe intensity of the combined output beam to the intensity of theintermediate beam may be less than 0.5, less than 0.4, less than 0.3,less than 0.2, less than 0.1, less than 0.05, approximately 0, and/orthe like). Thus, the ratio of the intensity of the combined output beam7 to the primary input beam 3 may be less than 0.25, less than 0.16,less than 0.09, less than 0.04, less than 0.01, less than 0.025,approximately 0, and/or the like. In various embodiments, a parallelring modulator 600 may be used to further decrease the ratio of theintensity of the combined output beam 7 compared to the intensity of theprimary input beam 3 in the low intensity/off state while having aminimal effect on the ratio of the intensity of the combined output beam7 compared to the intensity of the primary input beam 3 in the highintensity/on state (e.g., due to the low loss of the modulator). Invarious embodiments, the extinction ratio between the high intensity/onstate to the low intensity/off state of the combined output beam 7 maybe approximately 40 dB or greater. In various embodiments, the parallelring modulator 600 may be switched between a high intensity/on state anda low intensity/off state quickly (e.g., at a frequency of approximately100 MHz or faster).

Exemplary Method of Fabricating an Integrated Active/Passive ModulatorUnit

FIG. 10 provides a flowchart illustrating processes, procedures,operations, and/or the like performed to fabricate a unit 100. FIGS.11A-11E provides cross-sectional views of an active portion 150 of aunit 100 at various points during the fabrication process. Starting atstep/operation 702 of FIG. 10, a first cladding layer 114 is depositedon the substrate 112. For example, a first cladding layer 114 comprisingoxide and/or dielectric (e.g., SiO₂) may be deposited on the substrate112. In various embodiments, the first cladding layer 114 mayelectrically and/or thermally isolate the passive waveguide 116 from thesubstrate 112.

At step/operation 704, a waveguide layer 116A is deposited onto thefirst cladding layer 114. For example, a waveguide layer 116A comprisingthe material (e.g., Al₂O₃, Si₃N₄, HfO₂, AlN, Ta₂O₅, and/or the like) ofthe passive waveguide 116 may be deposited onto the first cladding layer114. FIG. 11A illustrates a cross-section of an active portion 150 of aunit 100 after completion of step/operation 704. For example, the firstcladding layer 114 is deposited on the substrate 112 and a layer of thepassive waveguide 116 material is deposited on the first cladding layer114 to form a waveguide layer 116A.

Continuing with FIG. 10, at step/operation 706, the waveguide layer 116Ais etched and/or patterned to form the passive waveguide 116. Forexample, the waveguide layer 116A may be etched and/or patterned to formthe passive waveguide 116 into the designed waveguide geometry. Invarious embodiments, a photolithography and/or mask etching process maybe used to etch the passive waveguide 116 from the waveguide layer 116A.At step/operator 708, a second cladding layer 118 is deposited. Forexample, the second cladding layer 118 is deposited onto the passivewaveguide 116 and the first cladding layer 114. For example, the secondcladding layer 118 comprising oxide and/or dielectric (e.g., SiO₂) maybe deposited on the first cladding layer 114 and the passive waveguide116. The exposed surface 119 of the second cladding layer 118 may bepolished (e.g., using chemical mechanical polishing (CMP)) so that theexposed surface 119 of the second cladding layer 118 is smooth and/orflat. FIG. 11B shows a cross-section of the active portion 150 of a unit100 after the second cladding layer 118 is deposited and polished (e.g.,via CMP).

Returning to FIG. 10, at step/operation 710, an active material blank800 is bonded onto the exposed layer 119 of the second cladding layer118. In various embodiments, as shown in FIG. 11C, the active materialblank 800 comprises an active layer 156A, and oxide layer 814, and ablank substrate 812. The active layer 156A may be made of the material(e.g., LiNbO₃, LiTaO₃, BaTiO₃, and/or the like) that is used to form theactive waveguide 156. Continuing with FIG. 10, at step/operation 712,the blank substrate 812 and the oxide layer 814 are removed. Forexample, etching may be used to remove the blank substrate 812 and theoxide layer 814.

At step/operation 714, the active layer 156A is etched for form theactive waveguide 156. For example, the active layer 156A may be etchedto form the downstream and upstream tapers 152A, 152B, the designedactive waveguide geometry, and/or the like. For example, the activewaveguide 156 may be formed by etching the active layer 156A. In variousembodiments, a photolithography and/or mask etching process may be usedto etch the active waveguide 156 from the active layer 156A. At step716, a third cladding layer 158 is deposited onto the active waveguide156 and/or the second cladding layer 118. For example, the thirdcladding layer 158 is deposited onto the active waveguide 156 and thesecond cladding layer 118. For example, the third cladding layer 158comprising oxide and/or dielectric (e.g., SiO₂) may be deposited on thesecond cladding layer 118 and the active waveguide 156. Atstep/operation 718, the exposed surface 159 of the third cladding layer158 is polished. For example, the exposed surface 159 of the thirdcladding layer 158 may be polished using CMP such that the exposedsurface is smooth and/or flat. FIG. 11D illustrates a cross-section ofthe active portion of a unit 100 after the polishing of the exposedsurface 159 of the third cladding layer 158.

Continuing with FIG. 10, at step/operation 720, via openings 174 (SeeFIG. 11E) are etched into the third cladding layer 158. For example, thevia openings 174 may be an opening etched into the third cladding layer158 such that vias may be deposited into the via openings 174 such thatthe vias are in electrical communication with the active waveguide 156.In various embodiments, a photolithography and/or mask etching processmay be used to etch the via openings 174 through the third claddinglayer 158. At step/operation 722, vias are deposited into the viaopenings 174 and onto the exposed surface 159 of the third claddinglayer 158. For example, a via material (e.g., a conductive material) maybe deposited into the via openings and on the exposed surface 159 of thethird cladding layer 158. At step/operation 724, the vias are patternedto form the electrical contacts 154. For example, excess via materialmay be etched away, polishing may be performed, and/or the like to formthe electrical contacts 154 from the deposited via material. In variousembodiments, a photolithography and/or mask etching process may be usedto etch the electrical contacts 154 from the deposited via material.FIG. 11E provides a cross-section of the active portion 150 of a unit100 after the electrical contacts 154 have been patterned.

In various embodiments, the unit 100 is a stand-alone device. In variousembodiments, one or more units 100 may be coupled to one another,additional passive waveguides (e.g., through passive waveguides, ring orloop passive waveguides, intermediate passive waveguides, and/or thelike) to provide a modulator. In various embodiments, the one or moreunits 100 may be coupled to one another and/or to additional passivewaveguides via one or more beam splitters and/or beam combiners. Forexample, the modulator may be an MZI modulator 200, cascaded MZImodulator 300, ring modulator 400, cascaded ring modulator 500, parallelring modulator 600, and/or the like. In various embodiments, themodulator may be a stand-alone device and/or element that may beincorporated into a photonic circuit, for example. In variousembodiments, the modulator is incorporated into and/or coupled to an iontrap of a trapped ion quantum computer. For example, the modulator maybe coupled to the ion trap so as to provide a modulated laser beam,and/or other modulated optical source, to one or more ions trappedwithin the ion trap.

Exemplary Quantum Computer Comprising a Modulator Comprising anIntegrated Active/Passive Modulator

FIG. 12 provides a schematic diagram of an example quantum computersystem 900 comprising an ion trap 50 having at least one modulator(e.g., MZI modulator 200, cascaded MZI modulator 300, ring modulator400, cascaded ring modulator 500, parallel ring modulator 600)comprising one or more units 100, in accordance with an exampleembodiment. In various embodiments, the quantum computer system 900comprises a computing entity 10 and a quantum computer 910. In variousembodiments, the quantum computer 910 comprises a controller 30, acryogenic and/or vacuum chamber 40 enclosing an ion trap 50, and one ormore manipulation sources 64 (e.g., 64A, 64B, 64C). In an exampleembodiment, the one or more manipulation sources 64 may comprise one ormore lasers (e.g., UV lasers, visible lasers, microwave lasers, and/orthe like). In various embodiments, the one or more manipulation sources64 are configured to manipulate and/or cause a controlled quantum stateevolution of one or more ions within the ion trap 50. For example, in anexample embodiment, wherein the one or more manipulation sources 64comprise one or more lasers, the lasers may provide one or more laserbeams to the ion trap 50 within the cryogenic and/or vacuum chamber 40.The one or more manipulation sources 64 each provide a laser beam and/orthe like to the ion trap 50 via a corresponding beam path 66 (e.g., 66A,66B, 66C). In various embodiments, at least one beam path 66 comprises amodulator (e.g., MZI modulator 200, cascaded MZI modulator 300, ringmodulator 400, cascaded ring modulator 500, parallel ring modulator 600)comprising one or more units 100. The modulator may be controlled by thecontroller 30 via one or more electrical signals 4 provided to theactive portion(s) 150 of the one or more units 100. For example, thecontroller 30 may cause one or more electrical signal sources, driversand/or the like to provide the electrical signal(s) 4. Via the modulator(e.g., comprising the one or more units 100) a manipulation source 64may provide a modulated beam, via a beam path 66, to the ion trap 50.

In various embodiments, a computing entity 10 is configured to allow auser to provide input to the quantum computer 910 (e.g., via a userinterface of the computing entity 10) and receive, view, and/or the likeoutput from the quantum computer 910. The computing entity 10 may be incommunication with the controller 30 of the quantum computer 910 via oneor more wired or wireless networks 20 and/or via direct wired and/orwireless communications. In an example embodiment, the computing entity10 may translate, configure, format, and/or the like information/data,quantum computing algorithms, and/or the like into a computing language,executable instructions, command sets, and/or the like that thecontroller 30 can understand and/or implement.

In various embodiments, the controller 30 is configured to control theelectrical signal sources and/or drivers, cryogenic system and/or vacuumsystem controlling the temperature and pressure within the cryogenicand/or vacuum chamber 40, manipulation sources 60, and/or other systemscontrolling the environmental conditions (e.g., temperature, humidity,pressure, and/or the like) within the cryogenic and/or vacuum chamber 40and/or configured to manipulate and/or cause a controlled evolution ofquantum states of one or more ions within the ion trap 50. In variousembodiments, the ions trapped within the ion trap 50 are used as qubitsof the quantum computer 910.

Exemplary Method of Fabricating an Integrated Modulator

In various embodiments, a modulator (e.g., MZI modulator 200, cascadedMZI modulator 300, ring modulator 400, cascaded ring modulator 500,parallel ring modulator 600) comprising one or more units 100 isintegrated into a beam path 66. For example, the modulator may beintegrated into an ion trap 50 so as to provide a beam path 66 thatprovides a modulated beam to the ion trap 50. For example, amanipulation source 64 may generated a continuous laser beam and/or apulsed laser beam. The laser beam may be provided to the ion trap 50 viathe beam path 66. As the beam path 66 comprises a modulator, the beam ismodulated by the modulator so that the beam provided to the ion trap 50is modulated.

In various embodiments, fabricating an integrated modulator includessteps/operations 702-722 of FIG. 10. Instead of proceeding fromstep/operation 722 to step/operation 724, the process may continue tostep/operation 734 of FIG. 13. At step/operation 734, vias are etched.For example, at step/operation 722, vias 155 are deposited into the viaopenings 174 etched through the third cladding layer 158. For example,FIG. 14A illustrates a cross-section of an active portion 150 of a unit100 after vias 155 have been deposited into the via openings 174 andetched.

Continuing with FIG. 13, at step/operation 736, additional cladding 168is deposited onto the vias 155 and third cladding layer 158. Forexample, additional cladding 168 comprising oxide and/or dielectric(e.g., SiO₂) may be deposited on the third cladding layer 158 and thevias 155. At step operation 738, the exposed surface 169 of theadditional cladding 168 is polished. For example, the exposed surface169 of the additional cladding 168 is polished (e.g., using CMP) tosmooth and/or flatten the exposed surface 169 of the additional cladding168. At step/operation 740, the via openings 174A are etched. Forexample, via openings 174A may be etched (e.g., via using a mask and/orthe like). For example, the via openings 174A are etched through theadditional cladding to the vias 155. In various embodiments, aphotolithography and/or mask etching process may be used to etch the viaopenings 174A through the additional cladding 168. FIG. 14B illustratesa cross-section of an active portion 150 of a unit 100 after the etchingof the via openings 174A.

Continuing FIG. 13, at step operation 742 vias are deposited into thevia openings 174 and onto the exposed surface 169 of the additionalcladding 168. For example, a via material (e.g., a conductive material)may be deposited into the via openings 174A and on the exposed surface169 of the additional cladding 168. In various embodiments, the vias aredeposited into electrical communication with the vias 155. Atstep/operation 744, the vias are patterned to form the electricalcontacts 154. For example, excess via material may be etched away (e.g.,using a mask and/or the like), polishing may be performed, and/or thelike to form the electrical contacts 154 from the deposited viamaterial. In various embodiments, a photolithography and/or mask etchingprocess may be used to etch the electrical contacts 154 from thedeposited via material. FIG. 14C provides a cross-section of the activeportion 150 of a unit 100 after the electrical contacts 154 have beenpatterned.

In various embodiments, the modulator (e.g., MZI modulators 200,cascaded MZI modulators 300, ring modulators 400, cascaded ringmodulators 500, parallel ring modulators 600, and/or the like) comprisesa beam splitter 202, beam combiner 204, beam splitter/combiner 402, 502,504, 602, 604, and/or the like. In various embodiments, the beamsplitters, beam combiners, and/or beam splitter/combiners may be variousoptical structures known in the art. In an example embodiment, the beamsplitter, beam combiner, and/or beam splitter/combiner may be embodiedas a direction coupler or photonic direction coupler. For example, thejunction between two passive elements (e.g., two passive portions 110A,110B, between a passive portion 110A, 110B and a passive waveguide 210,410, 505, and/or between two passive waveguides 210, 410, 505) includespositioning the two passive elements close together. For example, thetwo passive elements may be positioned, at the junction between the twopassive elements, such that the nominal claddings surrounding thepassive waveguides of the passive elements are in physical contact withone another. In an example embodiment, the beam splitter, beam combiner,and/or beam splitter/combiner may be embodied as a multimodeinterference coupler. For example, the junction between two passiveelements (e.g., two passive portions 110A, 110B, between a passiveportion 110A, 110B and a passive waveguide 210, 410, 505, and/or betweentwo passive waveguides 210, 410, 505) includes positioning the twopassive elements close together such that the passive waveguides of thepassive elements are in physical contact with one another for a givendesigned length.

Technical Advantages

Various embodiments provide integrated active/passive modulator units100 and/or modulators (e.g., MZI modulators 200, cascaded MZI modulators300, ring modulators 400, cascaded ring modulators 500, parallel ringmodulators 600, and/or the like) comprising one or more units 100. Theunits 100 are configured to change the phase of input photon beam withrelatively low loss. In various embodiments, the input photon beam has apower of approximately 100 mW or more. In various embodiments, the unit100 and/or a modulator comprising one or more units is configured toreceive an input beam and/or provide an output beam (and/or a combinedoutput beam) for a broad range of wavelengths. For example, the inputphoton beam (and/or output beam and/or combined output beam) may be avisible or UV beam (e.g., in the wavelength range of approximately350-1000 nm).

In various embodiments, a modulator comprising one or more units 100provides an extinction ration between the high intensity/on state andthe low intensity/off state of the combined output beam of at leastapproximately 40 dB. Moreover, a modulator comprising one or more units100 may be configured to modulate a beam between a high intensity/onstate and a low intensity/off state at a frequency of approximately 100MHz or faster.

The ability of the unit 100 to handle high power UV beams is providedvia the tapered geometry of the active portion 150 of the unit 100. Forexample, the tapered geometry of the active portion 150 may be designedto control the optical field and/or mode of the beam that is coupledinto the active waveguide 156 and/or coupled back into the passivewaveguide 116 from the active waveguide 156. Additionally, the loss ofthe unit 100 is reduced and the ability of the unit 100 to handle highpower visible and UV beams is increased by reducing and/or minimizingthe portion of the optical path through the unit 100 that is in theactive waveguide 156.

Thus, various embodiments of the integrated passive/active unit and/ormodulators comprising one or more units may be used to performcontrolled beam delivery of quickly modulated, high power beams in a lowloss manner and with a high level of beam placement accuracy.Additionally, modulators comprising one or more units require less spacethan free optic paths and free space AOMs.

Exemplary Controller

In various embodiments, a modulator (e.g., an MZI modulator 200,cascaded MZI modulator 300, ring modulator 400, cascaded ring modulator500, parallel ring modulator 600, and/or the like) comprising one ormore units 100 is incorporated into a quantum computer 910. In variousembodiments, a quantum computer 910 further comprises a controller 30configured to control various elements of the quantum computer 910. Forexample, the controller 30 may be configured to control the voltagesources and/or drivers configured to provide electrical signal(s) 4 tocontrol the modulation of one or more beams via the modulator(s), acryogenic system and/or vacuum system controlling the temperature andpressure within the cryogenic and/or vacuum chamber 40, manipulationsources 60, and/or other systems controlling the environmentalconditions (e.g., temperature, humidity, pressure, and/or the like)within the cryogenic and/or vacuum chamber 40 and/or configured tomanipulate and/or cause a controlled evolution of quantum states of oneor more ions within the ion trap 50.

As shown in FIG. 15, in various embodiments, the controller 30 maycomprise various controller elements including processing elements 1005,memory 1010, driver controller elements 1015, a communication interface1020, analog-digital converter elements 1025, and/or the like. Forexample, the processing elements 1005 may comprise programmable logicdevices (CPLDs), microprocessors, coprocessing entities,application-specific instruction-set processors (ASIPs), integratedcircuits, application specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), programmable logic arrays (PLAs),hardware accelerators, other processing devices and/or circuitry, and/orthe like. and/or controllers. The term circuitry may refer to anentirely hardware embodiment or a combination of hardware and computerprogram products. In an example embodiment, the processing element 1005of the controller 30 comprises a clock and/or is in communication with aclock.

For example, the memory 1010 may comprise non-transitory memory such asvolatile and/or non-volatile memory storage such as one or more of ashard disks, ROM, PROM, EPROM, EEPROM, flash memory, MMCs, SD memorycards, Memory Sticks, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory,RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory,and/or the like. In various embodiments, the memory 1010 may store qubitrecords corresponding the qubits of quantum computer (e.g., in a qubitrecord data store, qubit record database, qubit record table, and/or thelike), a calibration table, an executable queue, computer program code(e.g., in a one or more computer languages, specialized controllerlanguage(s), and/or the like), and/or the like. In an exampleembodiment, execution of at least a portion of the computer program codestored in the memory 1010 (e.g., by a processing element 1005) causesthe controller 30 to perform one or more steps, operations, processes,procedures and/or the like described herein for tracking the phase of anatomic object within an atomic system and causing the adjustment of thephase of one or more manipulation sources and/or signal(s) generatedthereby.

In various embodiments, the driver controller elements 1015 may includeone or more drivers and/or controller elements each configured tocontrol one or more drivers. In various embodiments, the drivercontroller elements 1015 may comprise drivers and/or driver controllers.For example, the driver controllers may be configured to cause one ormore corresponding drivers to be operated in accordance with executableinstructions, commands, and/or the like scheduled and executed by thecontroller 30 (e.g., by the processing element 1005). In variousembodiments, the driver controller elements 1015 may enable thecontroller 30 to operate a manipulation source 64, provide an electricalsignal 4 to an active portion 150 of at least one unit 100, and/or thelike. In various embodiments, the drivers may be laser drivers; vacuumcomponent drivers; drivers for controlling the flow of current and/orvoltage of an electrical signal 4 applied to an active portion 150 of aunit 100; cryogenic and/or vacuum system component drivers; and/or thelike. In various embodiments, the controller 30 comprises means forcommunicating and/or receiving signals from one or more optical receivercomponents such as cameras, MEMS cameras, CCD cameras, photodiodes,photomultiplier tubes, and/or the like. For example, the controller 30may comprise one or more analog-digital converter elements 1025configured to receive signals from one or more optical receivercomponents, calibration sensors, and/or the like.

In various embodiments, the controller 30 may comprise a communicationinterface 1020 for interfacing and/or communicating with a computingentity 10. For example, the controller 30 may comprise a communicationinterface 1020 for receiving executable instructions, command sets,and/or the like from the computing entity 10 and providing outputreceived from the quantum computer 910 (e.g., from an optical collectionsystem) and/or the result of a processing the output to the computingentity 10. In various embodiments, the computing entity 10 and thecontroller 30 may communicate via a direct wired and/or wirelessconnection and/or one or more wired and/or wireless networks 20.

Exemplary Computing Entity

FIG. 16 provides an illustrative schematic representative of an examplecomputing entity 10 that can be used in conjunction with embodiments ofthe present invention. In various embodiments, a computing entity 10 isconfigured to allow a user to provide input to the quantum computer 910(e.g., via a user interface of the computing entity 10) and receive,display, analyze, and/or the like output from the quantum computer 910.

As shown in FIG. 16, a computing entity 10 can include an antenna 1112,a transmitter 1104 (e.g., radio), a receiver 1106 (e.g., radio), and aprocessing element 1108 that provides signals to and receives signalsfrom the transmitter 1104 and receiver 1106, respectively. The signalsprovided to and received from the transmitter 1104 and the receiver1106, respectively, may include signaling information/data in accordancewith an air interface standard of applicable wireless systems tocommunicate with various entities, such as a controller 30, othercomputing entities 10, and/or the like. In this regard, the computingentity 10 may be capable of operating with one or more air interfacestandards, communication protocols, modulation types, and access types.For example, the computing entity 10 may be configured to receive and/orprovide communications using a wired data transmission protocol, such asfiber distributed data interface (FDDI), digital subscriber line (DSL),Ethernet, asynchronous transfer mode (ATM), frame relay, data over cableservice interface specification (DOCSIS), or any other wiredtransmission protocol. Similarly, the computing entity 10 may beconfigured to communicate via wireless external communication networksusing any of a variety of protocols, such as general packet radioservice (GPRS), Universal Mobile Telecommunications System (UMTS), CodeDivision Multiple Access 2000 (CDMA2000), CDMA2000 1× (1×RTT), WidebandCode Division Multiple Access (WCDMA), Global System for MobileCommunications (GSM), Enhanced Data rates for GSM Evolution (EDGE), TimeDivision-Synchronous Code Division Multiple Access (TD-SCDMA), Long TermEvolution (LTE), Evolved Universal Terrestrial Radio Access Network(E-UTRAN), Evolution-Data Optimized (EVDO), High Speed Packet Access(HSPA), High-Speed Downlink Packet Access (HSDPA), IEEE 802.11 (Wi-Fi),Wi-Fi Direct, 802.16 (WiMAX), ultra wideband (UWB), infrared (IR)protocols, near field communication (NFC) protocols, Wibree, Bluetoothprotocols, wireless universal serial bus (USB) protocols, and/or anyother wireless protocol. The computing entity 10 may use such protocolsand standards to communicate using Border Gateway Protocol (BGP),Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS),File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), HTTPover TLS/SSL/Secure, Internet Message Access Protocol (IMAP), NetworkTime Protocol (NTP), Simple Mail Transfer Protocol (SMTP), Telnet,Transport Layer Security (TLS), Secure Sockets Layer (SSL), InternetProtocol (IP), Transmission Control Protocol (TCP), User DatagramProtocol (UDP), Datagram Congestion Control Protocol (DCCP), StreamControl Transmission Protocol (SCTP), HyperText Markup Language (HTML),and/or the like.

Via these communication standards and protocols, the computing entity 10can communicate with various other entities using concepts such asUnstructured Supplementary Service information/data (USSD), ShortMessage Service (SMS), Multimedia Messaging Service (MMS), Dual-ToneMulti-Frequency Signaling (DTMF), and/or Subscriber Identity ModuleDialer (SIM dialer). The computing entity 10 can also download changes,add-ons, and updates, for instance, to its firmware, software (e.g.,including executable instructions, applications, program modules), andoperating system.

The computing entity 10 may also comprise a user interface devicecomprising one or more user input/output interfaces (e.g., a display1116 and/or speaker/speaker driver coupled to a processing element 1108and a touch screen, keyboard, mouse, and/or microphone coupled to aprocessing element 1108). For instance, the user output interface may beconfigured to provide an application, browser, user interface,interface, dashboard, screen, webpage, page, and/or similar words usedherein interchangeably executing on and/or accessible via the computingentity 10 to cause display or audible presentation of information/dataand for interaction therewith via one or more user input interfaces. Theuser input interface can comprise any of a number of devices allowingthe computing entity 10 to receive data, such as a keypad 1118 (hard orsoft), a touch display, voice/speech or motion interfaces, scanners,readers, or other input device. In embodiments including a keypad 1118,the keypad 1118 can include (or cause display of) the conventionalnumeric (0-9) and related keys (#, *), and other keys used for operatingthe computing entity 10 and may include a full set of alphabetic keys orset of keys that may be activated to provide a full set of alphanumerickeys. In addition to providing input, the user input interface can beused, for example, to activate or deactivate certain functions, such asscreen savers and/or sleep modes. Through such inputs the computingentity 10 can collect information/data, user interaction/input, and/orthe like.

The computing entity 10 can also include volatile storage or memory 1122and/or non-volatile storage or memory 1124, which can be embedded and/ormay be removable. For instance, the non-volatile memory may be ROM,PROM, EPROM, EEPROM, flash memory, MMCs, SD memory cards, Memory Sticks,CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, and/or the like. Thevolatile memory may be RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDRSDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cachememory, register memory, and/or the like. The volatile and non-volatilestorage or memory can store databases, database instances, databasemanagement system entities, data, applications, programs, programmodules, scripts, source code, object code, byte code, compiled code,interpreted code, machine code, executable instructions, and/or the liketo implement the functions of the computing entity 10.

CONCLUSION

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which theinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

That which is claimed:
 1. An integrated passive/active modulator unitcomprising: a passive waveguide extending a first length between anupstream passive end and a downstream passive end and having a widththat is substantially maintained along the first length; and an activeportion extending a second length between an upstream active end and adownstream active end, wherein the active portion comprises a taperedactive waveguide optically coupled to a portion of the passivewaveguide.
 2. The integrated passive/active modulator unit according toclaim 1, wherein the tapered active waveguide comprises an upstreamtaper having an increasing width in a beam propagation direction of theintegrated passive/active modulator unit, a central portion having asubstantially constant width, and a downstream taper having a decreasingwidth in the beam propagation direction.
 3. The integratedpassive/active modulator unit according to claim 2, wherein the upstreamtaper is configured to optically couple the active waveguide to anupstream portion of the passive waveguide and the downstream taper isconfigured to optically couple the active waveguide to a downstreamportion of the active waveguide.
 4. The integrated passive/activemodulator unit according to claim 2, wherein at least one of (i) theincreasing width of the upstream taper increases or (ii) the decreasingwidth of the downstream taper decreases as one of (a) linearly, (b)quadratically, (c) exponentially, or (d) as a portion of a period of acosine function.
 5. The integrated passive/active modulator unitaccording to claim 1, wherein the active portion further compriseselectrical contacts in electrical communication with the activewaveguide.
 6. The integrated passive/active modulator unit according toclaim 1, wherein at least one of the active waveguide or the passivewaveguide is configured to transmit and/or modulate a photonic beamcharacterized by a wavelength in a range substantially of 350-1000 nm.7. The integrated passive/active modulator unit according to claim 1,wherein the second length is less than the first length.
 8. A modulatorcomprising: at least one passive/active modulator unit comprising: apassive waveguide extending a first length between an upstream passiveend and a downstream passive end and having a width that issubstantially maintained along the first length; and an active portionextending a second length between an upstream active end and adownstream active end, wherein the active portion comprises a taperedactive waveguide optically coupled to a portion of the passivewaveguide; and at least one additional passive waveguide coupled to theupstream passive end and the downstream passive end via one or more beamsplitters and/or beam combiners.
 9. The modulator according to claim 8,wherein a beam combiner of the one or more beam splitters and/or beamcombiners is configured to couple a first beam output by at thedownstream passive end with a second beam to cause interference of thefirst beam and the second beam.
 10. The modulator according to claim 8,wherein the at least one passive/active modulator unit comprises twopassive/active modulator units coupled to one another in parallel. 11.The modulator according to claim 8, wherein the at least onepassive/active modulator unit comprises a first pair of passiveactive/modulator units and a second pair of passive active/modulatorunits, the first pair of passive active modulator units coupled to oneanother in parallel, the second pair of passive active modulator unitscoupled to one another in parallel, and the first pair of passive activemodulator units serially coupled to the second pair of passive activemodulator units.
 12. The modulator according to claim 8, wherein the atleast one passive/active modulator unit is formed into a ring such thatboth the upstream passive portion and the downstream passive portion arecoupled to a same additional passive waveguide.
 13. The modulatoraccording to claim 8, wherein the at least one additional passivewaveguide comprises a through passive waveguide and a ring passivewaveguide, the ring passive waveguide is configured to couple light intoand out of the through passive waveguide, and the at least onepassive/active modulator unit is formed into a ring such that both theupstream passive portion and the downstream passive portion are coupledto the ring passive waveguide.
 14. The modulator according to claim 8,wherein the at least one integrated passive/active modulator unitcomprises at least two integrated passive/active modulator units eachformed into a ring such that both the upstream portion and thedownstream portion of a first unit of the at least two integratedpassive/active modulator units are coupled to a same additional passivewaveguide and both the upstream portion and the downstream portion of asecond unit of the at least two integrated passive/active modulatorunits are coupled to the same additional passive waveguide, and thefirst unit and the second unit are serially coupled to the sameadditional passive waveguide.
 15. The modulator according to claim 8,wherein the integrated passive/active modulator is configured to providea combined output beam that can be modulated between a high intensity/onstate and a low intensity/off state with a frequency substantially equalto or greater than 100 MHz.
 16. The modulator according to claim 8,wherein the modulator is configured to provide a combined output beamthat has an extinction ratio between a high intensity/on state and a lowintensity/off state substantially equal to or greater than 40 dB. 17.The modulator according to claim 8, wherein the second length being lessthan the first length.
 18. A method of fabricating a modulator, themethod comprising: depositing a first cladding layer on a substrate;depositing a passive waveguide layer on the first cladding layer andpatterning the passive waveguide layer to provide a passive waveguideextending a first length between a first passive end and a secondpassive end, a width of the passive waveguide substantially maintainedalong the first length; depositing a second cladding layer on thepassive waveguide and the first cladding layer so as to at leastpartially enclose the passive waveguide; defining an active portion ofan integrated passive/active modulator unit by bonding an active layerto a portion of the second cladding layer; etching the active layer toform an active waveguide comprising at least one of an upstream taper ora downstream taper; and depositing and patterning electrical contacts inelectrical communication with the active waveguide.
 19. The methodaccording to claim 18, further comprising: depositing a third claddinglayer on the active portion; and etching via openings in the thirdcladding layer, wherein the electrical contacts are at least partiallydisposed within the via openings.
 20. The method according to claim 18,wherein the active layer is made of a first material, the first materialcharacterized by the refractive index of the first material changing inresponse to an electrical signal applied to the electrical contacts. 21.The method according to claim 18, wherein the width of the passivewaveguide is configured such that when a photonic beam characterized bya wavelength in a range substantially of 350-1000 nm and having a powerin a range of approximately 100-300 mW propagates through the passivewaveguide, the intensity of the photonic beam in a unit area of thepassive waveguide is less than a damage threshold intensity for amaterial of the passive waveguide.
 22. The method according to claim 18,wherein the upstream taper is configured to optically couple the activewaveguide to an upstream portion of the passive waveguide and thedownstream taper is configured to optically couple the active waveguideto a downstream portion of the active waveguide.